In this work the typical series of the remaining Synergus species described by Giraud are studied. The lectotypes of each one are designated. Synergus consobrinus is redescribed, S. variabilis Mayr, 1872 (= S. cerridis n. syn.) (= S. conformis n. syn.) and S. diaphanus are characterized. The respective synonymies for the rest of the studied species are established. Finally, biological data of some of the species are given and the distribution area of some of them is widened.
Hymenoptera, Cynipidae, synergini, Synergus, Giraud, lectotypes, systematics, synonymies, hosts.